Development and validation of an instrument to assess movement quality of the basketball free throw shooting

When a physical activity professional is teaching a motor skill, he evaluates the movement's learner and considers which interventions could be done at the moment. However, many times the instructor does not have such resources which could help him/her to evaluate the learner movement. The skill acquisition process could be facilitated if instructors could have an instrument that identifies errors, prioritizing information to be given to the learner. Considering that the specialized literature presents a lack of information about such tool, the purpose of this study was to develop, and to determine the objectivity and reliability of an instrument to assess the movement quality of the basketball free throw shooting. The checklist was developed and evaluated by basketball experts. Additionally, the checklist was used to assess 10 trials (edited video) from four individuals in different learning stages. Data were organized by the critical error and the error sum appointed by the experts in two different occasions (one week interval). Contrasting both evaluations, and also, contrasting different experts assessments, in sum and critical error, it was observed an average error of 16.9%. It was concluded that the checklist to assess the basketball free throw is reliable, and could help instructors to make a qualitative analysis. Moreover, the checklist may allow instructors to make assumptions on the motor learning process.

Effects of Methylphenidate on performance of a practical pistol shooting task: a quantitative electroencephalography (qEEG) study

Abstract Background The present study examined absolute alpha power using quantitative electroencephalogram (qEEG) in bilateral temporal and parietal cortices in novice soldiers under the influence of methylphenidate (MPH) during the preparatory aiming period in a practical pistol-shooting task. We anticipated higher bi-hemispheric cortical activation in the preparatory period relative to pre-shot baseline in the methylphenidate group when compared with the control group because methylphenidate has been shown to enhance task-related cognitive functions. Methods Twenty healthy, novice soldiers were equally distributed in control (CG; n = 10) and MPH groups 10 mg (MG; n = 10) using a randomized, double blind design. Subjects performed a pistol-shooting task while electroencephalographic activity was acquired. Results We found main effects for group and practice blocks on behavioral measures, and interactions between group and phases on electroencephalographic measures for the electrodes T3, T4, P3 and P4. Regarding the behavioral measures, the MPH group demonstrated significantly poorer in shooting performance when compared with the control and, in addition, significant increases in the scores over practice blocks were found on both groups. In addition, regarding the electroencephalographic data, we observed a significant increase in alpha power over practice blocks, but alpha power was significantly lower for the MPH group when compared with the placebo group. Moreover, we observed a significant decrease in alpha power in electrodes T4 and P4 during PTM. Conclusion Although we found no correlation between behavioral and EEG data, our findings show that MPH did not prevent the learning of the task in healthy subjects. However, during the practice blocks (PBs) it also did not favor the performance when compared with control group performance. It seems that the CNS effects of MPH demanded an initial readjustment period of integrated operations relative to the sensorimotor system. In other words, MPH seems to provoke a period of initial instability due to a possible modulation in neural activity, which can be explained by lower levels of alpha power (i.e., higher cortical activity). However, after the end of the PB1 a new stabilization was established in neural circuits, due to repetition of the task, resulting higher cortical activity during the task. In conclusion, MPH group performance was not initially superior to that of the control group, but eventually exceeded it, albeit without achieving statistical significance.

Cinema = cavação: Cendroswald produções cinematográficas

Em 1924, Blaise Cendrars, em meio a um projeto ambicioso de realização de um “filme de propaganda sobre o Brasil”, em parceria com Oswald de Andrade, teve a oportunidade de testemunhar a eclosão da Revolução de 1924, reprimida com violência pelo governo federal. A experiência marcou a sua imaginação e sepultou os planos de realizar um filme no Brasil, baseado em episódios da história paulista. Um dos elementos que aproximaram Oswald e Cendrars foi o desejo comum de se tornarem cineastas-cavadores

A simple and effective air shotgun for collecting small birds and other vertebrates at close range

Scientific collections are important sources of material for many areas of ornithological research. Although firearms (particularly shotguns) have been the standard for avian scientific collecting for more than 100 years, their use is restricted in many areas of the world. We describe a cheap, relatively silent, and effective air shotgun for collecting birds weighing up to 50 g at distances up to 4 m. This air shotgun is capable of shooting birdshot, uses hollow metal rivets connected to plastic straws as shot shells, and represents a simple adaptation of any 0.177 or 0.22 cal single-shot, break-barrel air rifle with at least 25 joules of muzzle energy. This air shotgun will be especially useful for focused sampling of birds (and other small vertebrates) in situations where firearm use or transport is restricted.

Energy demands in taekwondo athletes during combat simulation

The purpose of this study was to investigate energy system contributions and energy costs in combat situations. The sample consisted of 10 male taekwondo athletes (age: 21 +/- 6 years old; height: 176.2 +/- 5.3 cm; body mass: 67.2 +/- 8.9 kg) who compete at the national or international level. To estimate the energy contributions, and total energy cost of the fights, athletes performed a simulated competition consisting of three 2 min rounds with a 1 min recovery between each round. The combats were filmed to quantify the actual time spent fighting in each round. The contribution of the aerobic (WAER), anaerobic alactic (W-PCR), and anaerobic lactic (Wleft perpendicularLA-right perpendicular) energy systems was estimated through the measurement of oxygen consumption during the activity, the fast component of excess post-exercise oxygen consumption, and the change in blood lactate concentration in each round, respectively. The mean ratio of high intensity actions to moments of low intensity (steps and pauses) was similar to 1:7. The W-AER, W-PCR and (Wleft perpendicularLA-right perpendicular) system contributions were estimated as 120 +/- 22 kJ (66 +/- 6%), 54 +/- 21 kJ (30 +/- 6%), 8.5 kJ (4 +/- 2%), respectively. Thus, training sessions should be directed mainly to the improvement of the anaerobic alactic system (responsible by the highintensity actions), and of the aerobic system (responsible by the recovery process between high- intensity actions).

Aggressiveness Overcomes Body-Size Effects in Fights Staged between Invasive and Native Fish Species with Overlapping Niches

Approximately 50 years ago, Nile tilapia were accidentally introduced to Brazil, and the decline of pearl cichlid populations, which has been intensified by habitat degradation, in some locations has been associated with the presence of Nile tilapia. There is, however, little strong empirical evidence for the negative interaction of non-native fish populations with native fish populations; such evidence would indicate a potential behavioural mechanism that could cause the population of the native fish to decline. In this study, we show that in fights staged between pairs of Nile tilapia and pearl cichlids of differing body size, the Nile tilapia were more aggressive than the pearl cichlid. Because this effect prevailed over body-size effects, the pearl cichlids were at a disadvantage. The niche overlap between the Nile tilapia and the pearl cichlid in nature, and the competitive advantage shown by the Nile tilapia in this study potentially represent one of several possible results of the negative interactions imposed by an invasive species. These negative effects may reduce population viability of the native species and cause competitive exclusion.

Is shell partitioning between the hermit crabs Pagurus brevidactylus and Pagurus criniticornis explained by interference and/or exploitation competition?

The effect of crab behaviour on shell-use dynamics was analysed, comparing both interference and exploitation behaviours between the hermit crabs Pagurus criniticornis and Pagurus brevidactylus. Although these species exhibited microhabitat separation, with P. criniticornis dominating (100%) in sandy substrates and P. brevidactylus (80%) on rocky shores, they overlapped in the rocky shore/sand interface (P. criniticornis, 53%; P. brevidactylus, 43%). Pagurus criniticornis occupied shells of Cerithium atratum in higher frequencies (84%) than P. brevidactylus (37%), which was hypothesized to be a consequence of competitive interactions combined with their ability to acquire and/or retain this resource. The species P. criniticornis was attracted in larger numbers to simulated gastropod predation events than was P. brevidactylus, which, on the few occasions that it moved before P. criniticornis, tended to be attracted more rapidly. Interspecific shell exchanges between these species were few, suggesting the absence of dominance relationships. The shell-use pattern in this species pair is thus defined by exploitation competition, which is presumed to be intensified in areas of microsympatry. These results differ from other studies, which found that interference competition through interspecific exchanges shapes shell use, indicating that shell partitioning in hermit crabs is dependent on the behaviour of the species involved in the contests.

Construção e validação de um instrumento de análise qualitativa do arremesso (lance-livre) do basquetebol

Quando o profissional da área de Educação Física está ensinando uma habilidade motora, ele procura avaliar o movimento realizado pelo aluno e reflete sobre quais intervenções poderiam ser feitas naquele momento. No entanto, muitas vezes, o professor não dispõe de recursos que possam auxiliá-lo no processo de avaliação do movimento a ser aprendido pelo aluno. O processo de aquisição habilidades motoras poderia ser facilitado se o professor dispusesse nesse momento de um instrumento que identificasse o erro(s) cometido(s), bem como, qual seria a informação prioritária a ser fornecida ao aprendiz. Portanto, como a literatura especializada apresenta escassez no que diz respeito a esse tipo de ferramenta, o objetivo do presente estudo foi construir, validar e testar a objetividade e fidedignidade de um instrumento (checklist) que avalia a qualidade do arremesso do basquetebol (lance livre). O checklist da habilidade foi desenvolvido e avaliado por especialistas da modalidade esportiva e, posteriormente, o checklist foi utilizado para analisar 10 arremessos (vídeo editado) de quatro indivíduos em diferentes fases de aprendizagem da habilidade. Os resultados foram organizados em função do erro crítico e somatória de erros verificados pelos especialistas em duas ocasiões com uma semana de intervalo. Contrastando as avaliações do mesmo avaliador e entre avaliadores, em ambas as medidas, observou-se um nível de erro médio de 16,9%. Concluiu-se, portanto que o checklist proposto no presente estudo é um instrumento de avaliação do lance livre consistente e, nesse sentido, pode auxiliar professores e técnicos na análise qualitativa do arremesso. Além disso, esse instrumento de avaliação permite fazer inferências sobre o processo de aprendizagem de indivíduos nessa habilidade.